1. Field of the Invention
The present invention is related to a block head structure of an electric toothbrush; and especially to such a block head structure of an electric toothbrush of which the block head can be changed, so that the block head with such an improved structure can be slipped over and connected to a driving end on the block handle of an electric toothbrush of different style.
2. Description of the Prior Art
An electric toothbrush is a tool for cleaning tooth filth by repeated vibrating to and fro of the bristles moved by an electric motor. By virtue that the bristles of the electric toothbrush is moved by the electric motor, and that the rotation speed of the motor and the vibrating frequencies of the bristles are steady, the tooth filth in the gaps of the teeth can be thoroughly cleared. In comparison with a conventional toothbrush, an electric toothbrush has the advantages of saving more time and effort in brushing teeth; therefore, more and more people use electric toothbrushes in the recent years.
Electric toothbrushes sold in the markets often each includes a block handle and a plurality of block heads, so that a block head on the block handle can be changed in use. In this way, a consumer needs only to buy a more expensive block handle suiting a plurality of block heads for use of all his family members. And when the bristles on a block head is curved and deformed due to long period using, he needs only to buy a new block head instead, and there is no necessity to change for a whole new set of electric toothbrush. This more meets economic efficiency.
The block head structure of an electric toothbrush of the present invention aims at an improvement on the conventional electric toothbrush with a changeable block head structure in order that a single structure can suit block handles of various brands of different manufacturers.
As shown in FIG. 1, a conventional electric toothbrush is comprised mainly of a block handle 10 and a block head 20.
Wherein the block handle 10 is provided for holding by a user, and is provided therein with a storage battery and a motor (not shown); it has a driving end 11 on the front end thereof, the driving end 11 has a driving axle 12 extending therefrom forwardly. When the user presses down a push button on the block handle 10, a motor can be activated to drive the driving axle 12 to rotate for 360 degrees or rotate rightwards and leftwards repeatedly.
The block head 20 is provided with a set of bristles 22 on the front end of a block head sleeve 21, and with a connecting portion 23 on the rear end of the block head sleeve 21. When the connecting portion 23 is slipped over and connected to the driving end 11 on the block handle 10 of the electric toothbrush, the driving axle 12 can drive the set of bristles 22 on the front end of the block head sleeve 21 for rotating rightwards and leftwards repeatedly.
It shall be explained here that, electric toothbrushes sold in the markets are divided into two kinds by the style of motion transmitting. The first kind allows the motor in the block handle 10 to directly drive the driving axle 12 for 360 degree rotation; when the block head 20 is driven, a means in the block head sleeve 21 converts the 360 degree rotating motion into repeated rightward and leftward rotating, thereby, the set of bristles 22 rotates rightwards and leftwards repeatedly. The second kind has the block handle 10 provided therein with a mechanical transmitting mechanism, in order that the driving axle 12 on the front end can rotate rightwards and leftwards repeatedly; thereby, the block head sleeve 21 of the block head 20 is driven to rotate rightwards and leftwards repeatedly; there is no complicated means required therein to change the mode of transmitting.
The above stated two kinds of conventional techniques both have their merits and demerits; while the present invention is an improvement upon the block head 20 of the second kind of conventional electric toothbrush. That is, the structure of the present invention can only be slipped over a conventional block handle 10 of which the driving axle 12 is operated in the way of rotating rightwards and leftwards repeatedly. The interior structure of the block head 20 of the conventional electric toothbrushes is as shown in FIG. 2:
Wherein a driving axle bush 30 is provided between the set of bristles 22 on the front end of the block head sleeve 21 and the connecting portion 23; when the connecting portion 23 is slipped over and connected to the driving end 11 on the block handle 10, the driving axle 12 can be inserted exactly in the driving axle bush 30 to engage therewith axially and radially, thereby, the driving axle 12 can rotate rightwards and leftwards repeatedly, and the driving axle bush 30 also can rotate rightwards and leftwards repeatedly to thereby drive the set of bristles 22.
Referring simultaneously to FIGS. 1 and 2, by the fact that the driving axle 12 and the driving axle bush 30 can only make motion transmission when they are engage with each other axially and radially, the driving axle 12 shall at least be provided with a driving surface 13 and an engaging recess 14. While the driving axle bush 30 is provided for inserting and engagement of the driving axle 12; therefore, the axle hole of the driving axle 12 is in the shape in corresponding to that of the driving surface 13 in order to be provided with a stop block 31. By mutual abutting of the stop block 31 and the driving surface 13 against each other, the two members are radially positioned; when the driving axle 12 is rotated rightwards and leftwards repeatedly, it moves the driving axle bush 30 to rotate rightwards and leftwards repeatedly therewith. And the driving axle bush 30 is provided with an elastic hook 32, when the driving axle 12 is inserted into the driving axle bush 30 to its proper position, the elastic hook 32 engages the engaging recess 14, so that the driving axle 12 and the driving axle bush 30 are axially positioned to further prevent the driving axle bush 30 from axial sliding when it is driven by the driving axle 12 to rotate rightwards and leftwards repeatedly.
The axial and radial engaging and positioning means for the above stated conventional driving axle 12 and the driving axle bush 30 are different in locations and designing depending on different manufacturers. For example, the U.S. Pat. No. 5,289,604 granted to Braun Aktiengesellschaft is a patent with the same device as shown in FIGS. 1 and 2; a conventional driving axle 12 disclosed in FIGS. 3 and 4 has its driving surface 13 and engaging recess 14 different from those of FIGS. 1 and 2, correspondingly, the driving axle bush 30 thereof must be differently designed for transmitting (this is a known technique, and will not be further stated in details). Additionally, those have similar structures include U.S. Pat. Nos. 5,054,149; 4,989,287; 4,827,552; 4,827,550 and 4,291,547 etc. The related structures disclosed in them are based on the same principle as shown in FIGS. 1-4. The present invention provides improvement on the conventional techniques that needs two related means for simultaneous axial and radial positioning and that may have positioning means different in locations and designing depending on different manufacturers.